Elements are added to tungsten electrodes to

• A. decrease corrosion resistance
• B. increase corrosion resistance
• C. lower the melting temperature
• D. elevate the melting temperature

Answer: (D)

Elements are added to tungsten electrodes to boost their performance under the extreme heat of TIG welding. Doping tungsten with oxides such as thorium, cerium, or lanthanum improves thermionic emission, meaning electrons are released more readily to start and sustain the arc. This allows the electrode to carry higher current with less tip erosion and at higher temperatures. That higher temperature stability effectively raises the electrode’s usable melting point, so it can perform reliably in demanding GTAW conditions. Corrosion resistance isn’t the goal here, and lowering the melting temperature would weaken performance; the aim is to increase the temperature capacity and emission efficiency, which is why elevating the effective melting temperature is the correct concept.